1. Field of the Invention
The present invention relates to a technique for detecting a vehicle that violates a restriction with regard to the weight.
2. Description of Related Art
On a highway and the like, the weight of a vehicle is regulated. In order to verify whether or not a vehicle obeys the regulation, an axle weight detecting apparatus (also referred to as the loading plate) for measuring a weight for each axle of the vehicle is installed on the way. It is desired to identify and record the over axle weight vehicle that does not obey the regulation with regard to an axle weight.
One example of the system for identifying and recording the over axle weight vehicle will be discussed below with reference to FIG. 1. This system is provided with: an axle weight detecting apparatus 2 installed on a lane 1 of a toll gate in a highway; a sensor S for detecting the vehicle at a predetermined position on a downstream side from the axle weight detecting apparatus 2; and a camera unit 4 installed on the downstream side from the sensor S.
The axle weight detecting apparatus 2 detects the axle weight and when the axle weight exceeds a predetermined maximum weight, generates an over axle weight signal and sends it to the camera unit 4 that is installed on the road side on the downstream side from the axle weight detecting apparatus 2.
The sensor S is a vehicle detecting apparatus that includes, for example, a pair of a phototransmitter and a photoreceiver. The sensor S detects the presence or absence of the vehicle at the detection position defined by the line determined to vertically intersect the traffic flow direction of the lane 1. When the light beam emitted by the phototransmitter is detected by the photoreceiver, the sensor S generates a signal of a vehicle flag F=0 indicating that the vehicle does not exist at the detection position to send the signal to the camera unit 4. When the light beam emitted by the phototransmitter is interrupted and is not detected by the photoreceiver, the sensor S generates a signal of a vehicle flag F=1 indicating that the vehicle exists at the detection position and sends the signal to the camera unit 4.
The camera unit 4 is installed on a downstream side that is separated by a predetermined distance from the detection position of the sensor S. The visual field of the camera in the camera unit 4 is oriented to the upstream side of the lane. The camera unit 4, when carrying out an image taking in synchronization with the timing when the head of the vehicle intersects the detection position, takes an image of the front of the vehicle.
The camera unit 4 is set at an over axle weight vehicle image storing mode when it receives the over axle weight signal from the axle weight detecting apparatus 2. The camera unit 4 gets the vehicle flag F from the sensor S. In the case of the vehicle flag F=1 which is received at the over axle weight vehicle image storing mode, the camera unit 4 automatically takes an image and then stores the image as an over axle weight vehicle image. With this operation, the image of the vehicle that firstly arrives as the detection position of the sensor S after the occurrence of the violation of the axle weight regulation, or the vehicle that exists at the detection position when the violation of the axle weight regulation occurred is stored as the over axle weight vehicle image.